Lamp for producing intermittent light



Aug. 6, 1935. c. H. BRASELTON L AMP FOR PRODUCING INTERM ITTENT LIGHT 2 Sheets-Sheet l INVENTOR Filed May 17, 1932 Aug. 6, 1935.

C. H. BRASELTON LAMP FOR PRODUCING INTERMITTENT LIGH' 2 Sheets-Sheet 2 Filed May 17, 1932 INVENTOR latented Augr 6, 1935 {PATENT OFFICE.

; LAMP FOR PRODUCING INTERMI'I'I'ENT LIGHT Chester H. Braselton, New'York, N. Y., assignor to Sirian Lamp Company, Newark, N. 1., a corporation of Delaware Application May 17, 1932, Serial No. 611,814

10 Claims. (01. 176-4)- This invention relates to gaseous discharge lamps and has for its principal object to produce a lamp which will light intermittently or flicker at predetermined intervals of time.

Another object of the invention is to provide a gaseous discharge lamp in which the discharge is restricted. to a limited area and the pressure of the gas in that area is permitted to fluctuate intermittently with temperature changes.

Another object of "the invention is to provide an electric lamp with an'inner vessel in which the. discharge is confined with means to permit gas to flow into and out of the v'esselas the temperature'of the gas therein changes.

Another object of the invention is to provide an electric lamp in whichthe change of pressure of the gas therein, due to absorption by the electrodes, is considerably reduced over those used in the prior art. v

Otheriobjects oi the invention and objects relating' to the construction and assembly 01' the various partswill be apparent as the description of the invention proceeds.

Several embodiments of the invention have 25 been illustrated in the accompanying drawings in which: I

Fig. 1 is a sectional front elevational view of a lamp embodying-the invention;

Fig, 2 is a sectional front elevational view 01 another embodiment of the structure shown in Fig. 3 is a sectional front elevational view of another embodiment showing a plurality oi elements; r

Fig. 4 is a sectional front elevational viewot still another embodiment. of the construction of Fig. 3; I

I Fig. 5 is a'sectional plan view taken on the line Fig. 6 is a sectional elevational view of a modifled form of the device shown in Fig. 4; and

Figs. '7 and 8 are enlarged sectional elevational views of two different embodiments of the electron emitting elements used in any oi the preced- -In my application filed June 3, 1930, entitled Electric discharge device", and having the Serial No. 459,048 I have shown and described a dis-' charge device which operates under a'new phe- 50 nomenon discovered by me and in which an electron emitting element is energized in the pres ence oi an ionizable gas. When the conditions of a v gas pressure and emissivity of the element and voltage along the element are right a discharge 56 lwill appear like a halo surrounding the element and producing illumination. This discharge is confined to the element and its cross-sectional size appears to depend largely on the pressure 0! the gas used as well as the kind of gas. It the pressure of the gas is increased thedischarge tends to hug the element more closely until it increased high enough the discharge will disappear completely. In the present invention I make use of this fact by providing a means for intermittently increasing and decreasing the 10 pressure of the gas. adjacent the element where the discharge will occur. To this end I provide a glass tube, having a restricted opening, surrounding the electron emitting element. The pressure of the gas when heated by the discharge 15 will greatly increase thus stopping the discharge. At the same time gas will rush out of the tube through the opening thereby decreasing the pressure inside of the tube and thus permitting the pressure of the gas in the tube to again equalize and the discharge to form again. The discharge heats the gas again and the operation is repeated intermittently.

One embodiment of the invention which may be preferred is shown in Fig. 1 in which an envelope vll is shown provided. with the usual press II for supporting the elements. A transparent tube I! of high temperature glass such as uviol glass or. quartz glass is fused to the press II and in such a way that a support rod it which is sealed in the press H has its upper and within the tube l2.

The upper end of the tube I! has its open upper end restricted as at H, and an electron emitting element It is positioned axially within the tube,

being attached at its lower end to the support rod I1 and at its upper end to the end of a support I rod it which is bent outwardly and downwardly parallel to the tube l2 and is sealed in the press H. y 1 Y The electron emitting element Il may be com- 40 posed of a coil ll of refractory wire, (see Fig. 7)

which has a high resistancesuch as tungsten,- molybdenum, tantalum, or the like, and this coil may be coated with an electron emitting. material ll. Any of the well known materials used for increasing the emission of electrons in thermionic devices may be employed, such as a mixture of barium and strontiumoxides, or one ormore of the other oxides lot the alkaline earth metals, held together and upon the wire with a $0 suitable binder. v

Another iorm ot electron emitting element 1Q shown in Fig. 8 where the coil II has its individin] turns coated with theelectron emitting niattrlal I. Other-type! at electron 'emittersmay be used such as one in which the electron emitting material is in the form of a rod. which extends through the center of a coil of resistance wire, or the coil may be intermittently coated with the material, or the material may be incorporated in the metal of the coil, such as the well known thoriated tungsten wire which may be prepared by treating tungsticacid and thorium nitrate.

It may be. desirable to increase the conductivity at the ends of electron emitting element and if so a coil of refractory wire 2i of two or three turns may surround the end of the element with.- out touching it and may have its ends welded to the adjacent support rod. Such an auxiliary coil receives a portion of the current which fiows through the gas adjacent the filament and, therefore, protects the end of thefilament which would perhaps become overheated due to, this additional current fiow.

In mounting the electron emitting element inside of the tube 12 it may be preferable to first attach the lower end of the support rod it before the tube i2 is fused to the press. The tube may be fused to the press by-providing a tubular elongation on the bottom thereof which may be inserted over the filament and support rod it before the press is formed passing down inside be added to increase the conductivity of the gas or for color effects. For instance the vapors of mercury, caesium, rubidium, or sodium may be used.

With the elements and tube mounted upon the press It in the manner indicated in Fig. 1 the bulb l0 may be connected to an exhaust pump in the usual manner and an oven placed over the bulb to raise the temperature thereof to in the neighborhood of 400 C.'or to as high a temperature as the glass will stand without softening in order to drive out occluded gases in the envelope and associated parts. Current may also be run through the filament to raise the temperature thereof to about 600 C.- This heat is continued until a high vacuum of approximately .5 micron is obtained and allot the gases have been removed'from theenvelope which is evident by no fluorescence when a high tension current from an induction coil is directed against the walls of the bulb. Current may then be increased through the filament and the temperature thereof slowly raised until it is a bright red when the temperature will be about 800 C. This drives out any binder in the electron emitting material and also certain occluded gases which have not yet' been removed. The pump continues to remove from the envelope thegases which are driven out of the elements or other parts.

When no more gas is-found in the envelope the oven may be raised and the filament heated to slightly less than 1200 C. to drive out any other occluded gases or vapors which may be present. The pump may then be shut off and a slight amount of an inert gas, such as neon. at a pressure of about k mm. may be admitted to the envelope and the filament current turned on again. This causes reddish spots of discharge should take about ten minutes, but if white spots appear it is an indication that other gases are present and the envelope should be exhausted again and'the process repeated.

When the activation is completed the pump may again be connected to the envelope and the gas pumped out until a high vacuum is again produced. The filament circuit may then be disconnected and the pump turned off and about 50 mm, of neon gas admitted into the envelope followed by about mm. of argon. The bulb may then be sealed oh and is ready'for use.

When the lamp is connected in a circuit by means of the lead-in wires 22 and 23 which are connected respectively to the support rods l3 and-i6, the element i5 is energized and the temperature thereof raised until it reaches an electron emitting temperature. Thereupon the discharge forms extending outwardly almost to the sides of the tube l2 and from end to end of the element. This discharge consists of luminous gas having the appearance of a bright white flame and creating considerable heat. As the temperature of the gas within the tube l2 is raised the discharge moves closer to the filament until its stops entirely. At the same time gas rushes out of. the opening I 4 at the top of the tube into the space within the bulb In Where the pressure is lower. 'The decrease in pressure within the tube l2 due tothe gas rushing out and the cooling thereof as the discharge stops,

permits the discharge to form again around the filament, and this process is repeated, the dis-.v charge forming intermittently as the pressure of the gas raises and lowers. By carefully determining the size of the tube I 2 in relation to the size of the electron emitting element and the I 4 voltage used for the lamp the intermittent flash of the discharge maybe timed so as' to come at Fig. 1 is shown in which the tube 24 is exactly similar to the tube I2 of Fig. 1 except that a pair of openings 25 are provided adjacentthe lower end of the tube. These openings facilitate weld- 'ing of the electron emitting element l5 to the lower support rod I3 as the welding electrodes may be inserted through the holes 25 to makethe weld. The lamp operates in exactly the same manner as the construction of Fig. 1 and the openings 25 as well as the hole 26 in the top should he designed to control the escape of the gas in the same manner as the opening ll does in the construction of Fig. 1..

In some cases it may be desired to have a pair of electron emitting elements each in its own individual tube. This may be done by the construction of Fig. 3 in which the envelope 2'! is provided with a press 28 in which are sealed a pair of heavy support rods- 29 and 30 and a central support rod 3|. The support rods 29 and 30 are relatively short similarly to the ordinary support rods of the lamp but the central sup- 45 intervals even as long as several seconds between and a central support rod 49. A pair of transof the height of the bulb. A tube 32, somewhatsimilar to the tubes described in the preceding figures, is provided mounted upon the support rod 29 with the lower end of the tube fused to the support rod while a. tube 33 similar to the tube 32 is provided mounted on 'thesupport rod 30 fused in a similar manner. The upper ends of the tubes 32 and 33 arepositioned in a bracket 34 which is provided with a pair of holes 35 and llto receive respectively the tubes 32 and 33 and a central depending flange 31 which may be welded tothe central support rod 3l to rigidly secure the bracket and the upper ends of the tube in position. Electron emitting elements '38 and 39 similar exactly to those already described may have their lower ends attached to the support rods 29 and 30 and their upper ends attached to a'connecting member 49 which may be welded to the upper ends of the central support rod 3|. The tubes 32 and 33 are provided with restricted upper openings 4| and 42 respectively so as to control the flow of gas in a manner already described. Lead wires 43 and 44 are connected to the support rods 29 and 30 respectively for making the connections to the lamp.

It will be evident that the elements 38 and 39 are connected in series so that a voltage double that of the preceding figures maybe used,as sumlng that the elements are the same length and there is no danger of the discharge localizing into an are between the high potential ends of the elements because these ends arecovered by the tubes 32 and 33, the only openings being at the upper ends of these tubes. In designing this structure care should be taken to have the,

same resistance and the same emissivity so. that the two elements of the lamp may be made to flicker in synchrony. The tendency, however, will be to do this because of the fact that the elements are in series and as the discharge collapses less current flows through the element. Hence the current rises and falls with the flicker and will tend to synchronize the operation of the two elements. I

It may. be desired to independently construct the tubular members with their electron emitting elements inserted so that these members may be merely attached to the press of the lamp before carrying on the exhausting process. If this is the case the construction of Fig. 4 may be used in which the envelope 45 is provided with a press 45 in which is sealed two support rods 41 and '48 parent tubes 50 and 5| may be provided out of 'similar material to that already described and fused at their lower ends upon short support rods '52 and 53 while the upper ends of the tubes may be fused upon short support rods 54 and 55 respectively. A pair of oppositely spaced holes 55 in the tube 58 and a pair of oppositely spaced holes 51 in the tube 5| may be positioned adjacent the upper end of the elements so as to facilitate welding the upper ends thereof to the support rods 54 and 55 and at the same time permitting the gas to. escape'--in a manner already described. In making these independent elements the support rods 54 and 55 may be initially fused in the ends of the tubes which are provided with the holes 55 and 51 and then the elements,

which have already been-welded tothe support "rods 52 and 53, may be welded to the support rods 54 and 55. Then subsequently the lower ends positioning of the tubes is facilitated. Here the press. 51 is provided with a pair of short support rods 58 and 59 and a'central support rod 50.- However, a depression 6| may be formed around the support rod 58 in the top of the press and a second depression 62 may be formed on the top of the press around the supportrod 59. The tube 63 may be provided with an elongated lower portion 64 or, greatly diminished diameter so that it will fit easily over the support rod 58 and into the depression 6|, while the tube 55 may be provided with a similar elongated portion 66 which will fit over the support rod 59 and into the depression 62. The depressions GI and 62 may be provided with a suitable insulating cement, such as crolite cement, so that the holes in the bottom ends of the tubes 63 and 65 are sealed with respect to the gas within the lamp, and there will be no possibility of a leakage discharge through these lower ends.

A support rod 51 may be fused in the upper end of the tube63 while a support rod 58 may be fused in the upper end of the tube 65. A pair of oppositely positioned holes 69 may be provided in the upper end of the tube 53 adjacent the end of the support rod 51, while a pair of holes 10 may be provided in the tube 65 adjacent the end of the support rod 68. A pair of electron emitting elements H and 12 may be welded respectively between the support rods 58 and 61, and 59 and 68. I

In constructing the tube of Fig. 6 the electron emitting elements Il and 12 are first welded at their lower ends to the support rods 58 and 59. Then the tubes 63 and 55 with the upper support rods 81 and 58 fused in place are slipped over the elements and the lower necks 64 and 66 of the tubes are inserted into the depressions BI and 52,- the cement-having been placed there to seal the ends. Then the upper ends of the elements "H and I2 are welded to the support rods 61 and 68., through the holes 69 and 10, provided in the top of the tubes, and the lamp is ready to be exhausted and filled with gas. When the tubes are positioned on the press the upper ends of the support rods 51 and 58 maybe welded to a connecting rod 13 which may be welded .to the center support rod 50. Thus the whole constructionis rigidly supported upon the press and the assembly may be easily and quickly accomplished.

A feature of the invention is the enclosure of the discharge by the inner envelope which has a communicating opening with the larger enused were thatwithin the inner envelope. The

device of the invention tends to greatly increase the life of the lamp as the slight amount of gas absorbed after many hours of burning is insufficient to greatly influence the total pressure within the outer envelope.

Many other modifications of the invention may be resorted to without departing from the spirit thereof and I do not, therefore, desire to be limited to what has been shown and described except as such limitations occur in the appended claims.

What I desire to secure by Letters Patent and claim is:

1. In a discharge device a continuous filamentary electron emitting element, a transparent tubular member surrounding said element and having a restricted opening therein, and an ionizablev gas surrounding said element and member.

2. In a discharge device'an .envelope, a support within said envelope, a single light-giving and electron-emitting element forming a continuous electrical conductor mounted upon said support, a transparent tubular member surrounding said element and having a restricted opening therein, and an ionizable gas within said envelope.

3. In a discharge device an envelope, a support within said envelope, a continuous filamentary electron emitting element mounted upon said support, a transparent tubular member surrounding said element and having a restricted opening therein, and an ionizable gas having a pressure sumcient normally to confine the ionization of said gas to the region immediately surrounding said element when said element is en ergized.

4. Ina discharge device an envelope, a support within said envelope, a continuous filamentary resistance wire mounted upon said support, a coating of electron emitting material on the surface of said wire, a transparent tubular member surrounding said wire and having a restricted opening therein, and an ionizable gas having a pressuresuificient to confine the ionization of said gas to the region of said filament when said filament is energized.

5. In a discharge device an envelope, a support within said envelope, a continuous filamentary resistance wire mounted on said support, a transparent tubular member surrounding said wire and having a restricted opening therein, and an ionizable gas surrounding said element and tubular member and having a pressure in the neighborhood of 200 mm. of mercury.

6. In a discharge device an envelope, a support .within said envelope, a tubular member fused to said support, an electron emitting element mounted within said tubular member, said tubular member having an opening at the top through which said element may protrude, and an ionizable gas surrounding said element and member and having a pressure such that the ionization of said gas will be confined to the region of said element when said element is energized.

7. In a discharge device an envelope, a support within said envelope, a transparent tubular member fused to said support and having a plurality of restricted openings therein, an electron emitting element mounted within said tubular member, and an ionizable gas having a pressure in the neighborhood of 200 mm. of mercury surrounding said element and member.

8. In a discharge device a plurality of electron emitting elements, a transparent tubular member having restricted openings therein surrounding each of said elements, and an ionizable gas surrounding said elements and members and having a pressure such that the ionization of said gas is confined to the region of .said elements when said elements are energized.

9. In a discharge device an envelope, a support within said envelope, a plurality of support rods mounted on said support, a plurality of tubular members mounted on said support rods, an electron emitting element within each tubular member, tubular members having restricted openings therein, and an ionizable gas within said envelope.

10. In a discharge device an envelope, a second envelope within said first envelope and having an opening communicating with said first envelope,

a continuous filamentary electrode within said second envelope and an inert gas within said envelopes.

CHESTER H. BRASELTON. 

